Environmental impacts and causes of conflict in the Horn of Africa : a review

The Horn of Africa region stands out amongst the planet's territories that are most volatile and vulnerable to armed violence. Conflicts have greatly affected the region over the past 50 years. The conflicts have disrupted the lives of people as well as the environment in ways that are not fully understood. Although armed conflict has generally had a negative impact on the environment, the environmental impact of conflict within the Horn of Africa has barely been evaluated. Similarly, our understanding that climate variability as well as change could have played a role in increasing or decreasing the impacts of conflicts within the Horn of Africa is insufficient. Therefore, this paper looks at the environmental impacts of conflict in the Horn of Africa since 1970 and also the role of climate variability in increasing or decreasing the impacts of conflict. Scientific publications as well as grey literature were reviewed with the aim to understand the status of past and present conflicts in the Horn of Africa, environmental impacts of conflict and the role of climate variability in decreasing or increasing impacts of conflict. The review demonstrates that conflict has extensive negative impacts on the environment in the Horn of Africa with main causes like grievances, government behaviour and interests, resource scarcity and trans border conflict as well as internal migration and climate variability. Similarly, climate variability plays a great role in exacerbating the impacts of conflict in the region. However, further research is needed to clearly show the impact of conflict and climate variability on the environment in the Horn of Africa

Can rangelands gain from bush encroachment? Carbon stocks of communal grazing lands invaded by Prosopis juliflora

This research article published by Elsevier Ltd., 2017Rangeland ecosystems are rapidly declining due to overgrazing and bush encroachment. Little is known about how important bush encroachment is for climate change mitigation. We estimated woody plant biomass at different Prosopis juliflora cover to quantify above- and below-ground carbon (C) stocks in Afar, northern Ethiopia. We developed allometric models to estimate aboveground biomass (agB) through destructive harvesting based on crown diameter (CrD), diameter at stump height (DSH), and tree height (H) for twenty P. juliflora and 18 Acacia senegal trees. DSH showed the best model fit in predicting above ground biomass compared to H, CrD, and the combination of those predictor parameters, respectively. Models were highly significant for all agB components. Total C stocks of the entire woody species community were about 40% higher (86 Mg C ha−1) at high than at low (50 Mg C ha−1) P. juliflora encroachment categories. We conclude that allometric models using simple dendrometric parameters are highly valuable for assessing P. juliflora biomass. While in lightly invaded areas, eradication and prevention of further spread might be possible, we propose that the high C stocks of rangelands densely invaded by P. juliflora, where eradication attempts have failed, should be considered for potential C trade measures

Variations in soil properties and native woody plant species abundance under Prosopis juliflora invasion in Afar grazing lands, Ethiopia

This research article published by Springer Nature, 2020Introduction Pastoralism and agro-pastoralism are the major modes of life in arid and semi-arid rangelands. However, rangeland quality and quantity are rapidly deteriorating due to a number of natural and human-induced factors, one of which is bush encroachment. Little is known on how bush encroachment affects the ecosystem functions and services expressed in terms of the native vegetation composition and structure, status of the soil seed bank, soil chemical and physical properties, and the abundance of mycorrhiza spores. Methods We assessed woody species in 64 plots distributed across four levels of Prosopis juliflora invasion (high, medium, low, and none) at two sites, Amibara and Gewane, in the Afar Region, Ethiopia. We collected composite soil samples to investigate the soil seed bank, mycorrhizal associations, and spore abundance. Results Plant biodiversity was generally low, with eight and four woody species in Gewane and Amibara, respectively. Prosopis juliflora was dominant in highly, moderately, and lowly invaded areas while Acacia senegal dominated the non-invaded areas. The average number of P. juliflora individuals ranged from 3/ha at non-invaded areas in Gewane to 4200/ha at highly invaded areas in Amibara while the total individual number of native woody species ranged from 0 to 88/ha at highly and lowly invaded areas, respectively. The population structure of trees/shrubs in all invasion areas showed an inverted J-shaped distribution, characterized by a high abundance of small individuals. Prosopis juliflora invasion was associated with high soil OC, Na, Ca, P, bulk density, and moisture content. Herbaceous seed numbers and species richness were highest in the moderately and highly invaded areas. All sampled tree species were associated with mycorrhiza but the percentage of root length colonization by different arbuscular mycorrhizal fungus structures varied significantly (p < 0.05) across invasion categories and sites. Conclusions Our results revealed that although P. juliflora invasion negatively impacted the availability of native woody livestock forage species, it had a positive effect on most soil physical and chemical properties. Such variable effects call out for sustainable management practices when invaded areas are restored

The Effect of the war on smallholder agriculture in Tigray, Northern Ethiopia

AbstractThe war in Tigray (Northern Ethiopia) that started at the beginning of November 2020 has brought devastating damage to smallholder agriculture and food security. However, empirical evidence on the effect of war on smallholder agriculture has not studied systematically. Thus, this research was initiated to address the knowledge gap. A survey was done on selected 4376 households using systematic random sampling. All the data required for the study was collected using a semi-structured questionnaire, focus group discussions and key informant interview. The study revealed that 81% of the smallholder households lost their crop followed by livestock (75%) and farm tools (48%). Overall, 94% of the households reported that at least one of their agricultural components (crop, livestock and farm tools) was looted and/or destroyed by the belligerents. Of which, 37% of the respondent’s crop, livestock and farm tools were totally damaged. Moreover, farmers have limited access to their farms, agricultural inputs, and services. Consequently, more than 5.2 million people are currently in need of immediate humanitarian assistance. To avert the worsening situation, immediate intervention is needed to deliver food and agricultural input supplies and rehabilitate the agricultural extension system and infrastructure

Carbon stock and soil properties Data

Soil properties and carbon stock data for semi-arid environment of northern Ethiopi

Tuberculosis-Human Immunodeficiency Virus (HIV) co-infection in Ethiopia: a systematic review and meta-analysis

Abstract Background Human Immunodeficiency Virus (HIV) and Tuberculosis (TB) are the double burden diseases of the world. The African continent takes a great share of TB-HIV cases worldwide. This study was aimed to determine the prevalence of TB-HIV co-infection in Ethiopia, using a meta-analysis based on a systematic review of published articles. Methods An electronic search was conducted in databases including PubMed, HINARI, EMBASE, Cochrane library and Google Scholar to extract the articles. Articles published between 1995 and November 2017 had been searched for using different keywords. The analysis was performed using MetaXL software and R statistical software (version 3.2.3). Result Our searches returned a total of (n = 26,746) records from 30 articles of which 21 were cross-sectional, 7 were retrospectives and 2 were prospective studies. The range of prevalence of TB-HIV co-infection was found to be from 6 to 52.1% with random effects pooled prevalence of 22% (95% CI 19–24%) and with substantial heterogeneity chi-square (X2 ) = 746.0, p < 0.001, (I 2  = 95.84%). Conclusion Our analysis indicated that the prevalence of TB-HIV co-infection is high in Ethiopia with substantial regional variation. An integrated, facility-based and community-based effort towards the prevention, early detection and management of cases should be further strengthened throughout the country to mitigate the double burden disease

The effects of land cover change on carbon stock dynamics in a dry Afromontane forest in northern Ethiopia

Abstract Background Forests play an important role in mitigating global climate change by capturing and sequestering atmospheric carbon. Quantitative estimation of the temporal and spatial pattern of carbon storage in forest ecosystems is critical for formulating forest management policies to combat climate change. This study explored the effects of land cover change on carbon stock dynamics in the Wujig Mahgo Waren forest, a dry Afromontane forest that covers an area of 17,000 ha in northern Ethiopia. Results The total carbon stocks of the Wujig Mahgo Waren forest ecosystems estimated using a multi-disciplinary approach that combined remote sensing with a ground survey were 1951, 1999, and 1955 GgC in 1985, 2000 and 2016 years respectively. The mean carbon stocks in the dense forests, open forests, grasslands, cultivated lands and bare lands were estimated at 181.78 ± 27.06, 104.83 ± 12.35, 108.77 ± 6.77, 76.54 ± 7.84 and 83.11 ± 8.53 MgC ha−1 respectively. The aboveground vegetation parameters (tree density, DBH and height) explain 59% of the variance in soil organic carbon. Conclusions The obtained estimates of mean carbon stocks in ecosystems representing the major land cover types are of importance in the development of forest management plan aimed at enhancing mitigation potential of dry Afromontane forests in northern Ethiopia

Data from: Carbon sequestration and soil restoration potential of grazing lands under exclosure management in a semi-arid environment of northern Ethiopia

Exclosures are used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, this study assessed the impact of grazing exclosure on vegetation biomass, carbon sequestration and soil nutrients under five and ten years of grazing exclosures and freely grazed areas in Tigray, northern Ethiopia. Vegetation biomass, carbon stocks and soil nutrients increased with increasing grazing exclusion. However, open grazing lands and five years of grazing exclosure did not differ in aboveground biomass, above-and-belowground carbon stocks. Moreover, ten years of grazing exclosure had a higher (P<0.01) grass, herb and litter carbon stocks compared to five years exclosure and open grazing lands. The total carbon stock was higher for ten years exclosure (75.65 t C ha-1) than the five years exclosure (55.06 t C ha-1) and in open grazing areas (51.98 t C ha-1). Grazing lands closed for ten years had a higher SOC, organic matter, total N, available P, and exchangeable K+ and Na+ compared to five year’s exclosure and open grazing lands. Therefore, establishment of grazing exclosures had a positive effect in restoring degraded grazing lands, thus improving vegetation biomass, carbon sequestration potentials and soil nutrients

Exclosures restored the density and root colonization of arbuscular mycorrhizal fungi in Tigray, Northern Ethiopia

Abstract Introduction Exclusion of grazing animals and tree plantations were among the methods used for the restoration of degraded lands in tropical semiarid areas. Exclosures can foster secondary forest succession by improving soil conditions and modifying microclimate for understory growth. This paper compared the arbuscular mycorrhizal fungi (AMF) spore density, root colonization of woody plants and soil chemical properties under exclosure with increasing age, and grazing land at different slope positions. Methods The study was conducted in northern Ethiopia from 12 exclosure sites paired each with adjacent grazing land in total from 24 sites with four treatments replicated three times. In the entire study, 216 plots were examined of which 108 were in exclosures and 108 in communal grazing lands. There were four age classes and three slope positions in each of the land uses. Composite soil and root samples were collected using nested plots measuring 100m2 from four sides of 1763 plants for spore enumeration and root colonization. Soils for chemical properties were collected from the four corners and center of 5 m × 5 m plots. Results All the 61 woody plant species that belong to 41 families were colonized by AMF. Spore density and root colonization were significantly higher in exclosures as compared to grazing land and increased with increasing ages of exclosures. Foot slope had significantly higher spore density and root colonization than middle and upper slopes. Soil chemical properties were significantly higher in the exclosure, oldest age of exclosure, and foot slope position (except P). AMF spore density and root colonization were significantly positively correlated with soil chemical properties. Conclusions Exclosures are helpful to restore the AMF spore density and root colonization of woody species and soil fertility

Carbon stocks and sequestration potential of dry forests under community management in Tigray, Ethiopia

Abstract Introduction Forests form a major component of the carbon (C) reserves in the world’s ecosystems. However, little is known on how management influences C stocks of woody vegetation, particularly in dry areas. We developed regression models for two dominant tree species to predict C stocks and quantified the potential of community managed forests as C sinks. Methods Plots were randomly selected from community-managed natural forest, herbivore exclosures, and from communal grazing land. Tree and shrub biomass were estimated using a regression model on the most dominant woody species while herbaceous biomass was determined using destructive sampling. Results The simplest model, based on only one single predictor variable, showed a good fit to the data for both species (Juniperus procera and Acacia abyssinica). Diameter at breast height (r 2 > 0.95) was a more reliable predictor than height (r 2 > 0.54), crown diameter (r 2 > 0.68) (p < 0.001). The C content of the total biomass for the managed natural forest and the exclosure were estimated as, 58.11 and 22.29 Mg ha−1, respectively, while that for the grazing land was 7.76 Mg ha−1, and the mean carbon content between the three land uses were significantly different (p < 0.05). Conclusions We conclude that forests managed by the community have a high potential for C sequestration and storage and their conservation should be promoted